In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.
Known rotatable tools comprising position adjustable cutting elements use various means for effecting changes of position of the cutting elements, including mechanical actuators, hydraulics and pneumatic pressure. Typically, the actuation device, such as a translating bar internal to the rotatable tool, was precisely fitted and had high friction surfaces, requiring high mechanically-generated or fluid-generated forces for actuation movement. Examples of known rotatable tools with position adjustable cutting elements are EP Patent Application No. 1123766, Japanese Utility Model Application No. 62-201231 and U.S. Pat. Nos. 4,941,782, 6,394,710 and 6,846,136.